6 comments:

How can you possibly measure something like how many hours of TV you've watched in your life? It would be hard for me to figure out how many hours of TV I watched this year, much less since 1950 when TV starting appearing. Since there was not TV in the 30s and 40s, you'd expect they would have lived longer in those years. The opposite seems to be the case. This sounds to me like trying to see causation in events which simply parallel each other. You'd have to eliminate all other possible causes to say it was TV that was the causal factor. How could you eliminate genetics, improvements in medicine and drugs, environmental factors like pollution and hundreds of other possible factors?

And, this is why we need improved AI technology, so that consumers can fool themselves into thinking they are exercising without the effort or the guilt that comes from not really moving. Seriously, why do these researchers want people to bother to move - to go shopping and spend money? populate theme parks? pack restaurants?

@ TC: I'm skeptical about the TV study, even when I'm among those who don't watch TV.

But the way they did it is that they asked how many hours they watched TV the week before the questionnaire. From that data they calculate and approximation to life time hours. It's all approximate, and there are lots of objections to this kind of approach, but that's the way they do it. Then they follow those people for many years, and figure out their longevity. So they may have found that people who reported more hours watching TV tended to die at a younger age than those who watched much less. It's the same cohort, so medical care, environmental factors, etc tend to be the same for everybody. The point isn't about watching TV but about sedentarism. Watching TV is a proxy for it.

I gave up smoking, and have never been into watching TV. But computers and chocolate are anothere story...

You have to make the assumption that watching TV precludes other activities. You could work out at the gym for two hours, then work at a physical job for the rest of the day and watch 4 hours of TV at the end of the day and not be short on exercise and movement.

I think it's a stretch to link TV watching to a sedentary lifestyle. Also you have to exclude things like smoking and a bad diet which may or may not be associated with TV watching. If you watch TV for an hour while you're walking on the treadmill at the gym it presumably wouldn't count. If you don't watch TV but you smoke two packs a day and have red meat at every meal, your life is arguably shorter than someone who eats a healthy diet, doesn't smoke but watches 4 hours of TV per day.

If you wanted to say that people who watch TV may have a shortened life expectancy since they probably do other bad things as well. I might accept that, but when you try to give an exact figure out to the tenths, I think it implies an exactitude of measurement that's impossible. Plus you're assuming that people who watch TV have other bad activities associated with that.

@TC: Remember how they're doing this study. They asked how many hours of TV were watched the week prior to the questionnaire. Respondents could have had the flu the week before, and had nothing else to do in bed but to watch TV all day. So, sure, there will be cases like that, when the time spent watching TV tells nothing about on going levels of activity/exercise. But when they have a very large sample, those outliers get lost by the most common circumstance: people who report watching TV for more hours tend to do that all the time, and it does reflect sedentarism.

In terms of calculating how much shorter your life would be in an exact number, it's silly. It's only a number that comes out of their statistical analysis, and has very limited value when you talk about individual cases.

There are certain variables (characteristics) that tend to cling together and it's difficult to tease them out unless you have extremely large samples. Sedentarism, overeating, obesity are all probably associated with excessive TV watching. But, you may have a sample that's large enough to look at each of those factors separately and see how each of them accounts for the variation.

Anyway, statistics are boring. And these studies seem to come and contradict each other. Common sense is to be used.

Did you see the article citing studies about being overweight and risk of death?